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21.
Ecohydrology and invasive ecology have become increasingly important in the context of global climate change. This study presents the first in-depth analysis of the water use of invasive and native plants of the same growth form at multiple scales: leaf, plant, and ecosystem. We reanalyzed data for several hundred native and invasive species from over 40 published studies worldwide to glean global trends and to highlight how patterns vary depending on both scale and climate. We analyzed all pairwise combinations of co-occurring native and invasive species for higher comparative resolution of the likelihood of an invasive species using more water than a native species and tested for significance using bootstrap methods. At each scale, we found several-fold differences in water use between specific paired invasive and native species. At the leaf scale, we found a strong tendency for invasive species to have greater stomatal conductance than native species. At the plant scale, however, natives and invasives were equally likely to have the higher sap flow rates. Available data were much fewer for the ecosystem scale; nevertheless, we found that invasive-dominated ecosystems were more likely to have higher sap flow rates per unit ground area than native-dominated ecosystems. Ecosystem-scale evapotranspiration, on the other hand, was equally likely to be greater for systems dominated by invasive and native species of the same growth form. The inherent disconnects in the determination of water use when changing scales from leaf to plant to ecosystem reveal hypotheses for future studies and a critical need for more ecosystem-scale water use measurements in invasive- vs. native-dominated systems. The differences in water use of native and invasive species also depended strongly on climate, with the greater water use of invasives enhanced in hotter, wetter climates at the coarser scales. 相似文献
22.
KATHLEEN E. HALVORSEN 《Environmental management》2001,28(2):179-186
Public participatory techniques have been the focus of a large and growing body of environmental literature. There is some
consensus among those who study these techniques that there is a need to develop and implement new techniques that meet certain
criteria. These include that the techniques be comfortable, convenient, and satisfying to participants. Authors have also
frequently called for the use of deliberative techniques, which allow participants to express and listen to a variety of perspectives
regarding the issue at hand. However, the literature on public participation lacks a set of widely applicable evaluation methods
to determine whether participants in techniques find them comfortable, convenient, satisfying, or deliberative. This paper
reports on the implementation of two different techniques that participants scored fairly high on all of these factors, as
well as the scale-based survey questions developed to measure these factors. 相似文献
23.
Environmental Chemistry Letters - Antibiotics are water and soil contaminants causing the development of multi-resistant bacteria, calling for advanced water treatments. For instance,... 相似文献
24.
25.
Wilbur H. Campbell Pengfei Song Guillaume G. Barbier 《Environmental Chemistry Letters》2006,4(2):69-73
Nitrate analysis in water is one of the most frequently applied methods in environmental chemistry. Current methods for nitrate are generally based on toxic substances. Here, we show that a viable alternative method is to use the enzyme nitrate reductase. The key to applying this Green Chemistry solution for nitrate analysis is plentiful, inexpensive, analytical grade enzyme. We demonstrate that recombinant Arabidopsis nitrate reductase, expressed in the methylotrophic yeast Pichia pastoris, is a highly effective catalyst for nitrate analysis at 37°C. Recombinant production of enzyme ensures consistent quality and provides means to meet the needs of environmental chemistry. 相似文献
26.
R. Stottlemyer Darcy Rutkowski David Toczydlowski 《Environmental monitoring and assessment》1989,12(1):65-65
Legally protected national parks provide an appropriate substrate for essential long-term study of ecosystem structure and function, and for detecting trends in natural and human-induced stress. The absence of unplanned site manipulation in such areas is especially valuable for such research. Our present research has two major components. The first is the long-term ecosystem-level study of the effects of atmospheric contaminants on ecosystem processes. The overall objective is to evaluate ecosystem aquatic/terrestrial linkages and their role in establishing aquatic ecosystem sensitivity to anthropic atmospheric inputs. Four watershed/lake ecosystems, representative of much of the region's diversity, are under study. Two mature boreal sites on Isle Royale are characterized by first-order perennial surface stream input and lake outflow. Two additional mainland northern hardwood sites, one with shallow soils and one with soils derived from glacial till, are characterized by sensitive aquatic systems. One site is in a private reserve and the other in Pictured Rocks National Lakeshore. Surface outflow is gaged by Parshall flume and stage height recorder. Meteorological stations record variables for estimating evapotranspiration. One-tenth ha plots have been established in all watersheds and three sites have had intensive study of precipitation modification by canopy and forest soil. Five-year mean maximum and minimum lake pH varies from 6.85 to 4.94, Ca2+ from 1070 to 54 eq l-1, K+ from 5.42 to 8.35 eq l-1, NH
4
+
from 10.12 to 3.23 eq l-1, HCO
3
sup-
from 635 to 24 eq l-1, NO
3
sup-
from 3.27 to 1.54 eq l-1, and SO
4
sup2-
from 110 to 52.7 eq l-1. The relatively high NO
3
sup-
values observed in one lake are the result of stream drainage from a watershed dominated by Alnus rugosa, and another has high seasonal NO
3
sup-
inputs during spring runoff. However, owing to periodic winter thaws, significant snowpack release of nutrients generally precedes maximum spring stream runoff. Water chemistry in both sensitive and non-sensitive lakes appears to be primarily reflecting how the conterminous terrestrial system is retaining atmospheric inputs more than the quality of direct lake atmospheric input. This is especially evident for H+, NO
3
sup-
and SO
4
sup2-
.The second component is the assessment of watershed acidification, SO
4
sup2-
output and soil retention across an input gradient. An anthropic deposition gradient provides the opportunity for intersite time-trend analyses as to the effects of inputs. Our study objective was to see if the decreasing west to east input/output values for SO
4
sup2-
, noted in small first-order watersheds in national parks from Minnesota to Ohio, might be related to present atmospheric inputs, potential and total soil SO
4
sup2-
adsorption, or soil SO
4
sup2-
desorption from earlier higher inputs. Precipitation pH ranged from 5.05 at Fernberg, Minnesota to 4.24 at Wooster, Ohio. Minimum and maximum concentrations of NH
4
+
, NO
3
sup-
, SO
4
sup2-
and Cl- were also found at these stations. Stream water concentrations of NO
3
sup-
and SO
4
sup2-
increase in a similar but sharper gradient. Streams are well buffered. Cation, HCO
3
sup-
, NO
3
sup-
and especially SO
4
sup2-
output increase west to east, but H+ output decreases. At the eastern site stream SO
4
sup2-
concentration and output exceed HCO
3
sup-
. Potential soil SO
4
sup2-
adsorption capacity increases eastward, but this capacity is filled. Crystalline Fe hydrous oxides appear more effective than amorphous Fe hydrous oxides at adsorbing SO
4
sup2-
. High anthropic anion inputs, inability of forest soil to adsorb additional inputs and perhaps SO
4
sup2-
desorption appear responsible for the replacement of HCO
3
sup-
by SO
4
sup2-
in stream water. The major cation accompanying SO
4
sup2-
is Ca2+.Contribution from Fourth World Wilderness Congress—Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987. 相似文献
27.
Asko Noormets Olevi Kull Mark E. Kubiske 《Environmental pollution (Barking, Essex : 1987)》2010,158(4):992-999
The effect of elevated CO2 and O3 on apparent quantum yield (?), maximum photosynthesis (Pmax), carboxylation efficiency (Vcmax) and electron transport capacity (Jmax) at different canopy locations was studied in two aspen (Populus tremuloides) clones of contrasting O3 tolerance. Local light climate at every leaf was characterized as fraction of above-canopy photosynthetic photon flux density (%PPFD). Elevated CO2 alone did not affect ? or Pmax, and increased Jmax in the O3-sensitive, but not in the O3-tolerant clone. Elevated O3 decreased leaf chlorophyll content and all photosynthetic parameters, particularly in the lower canopy, and the negative impact of O3 increased through time. Significant interaction effect, whereby the negative impact of elevated O3 was exaggerated by elevated CO2 was seen in Chl, N and Jmax, and occurred in both O3-tolerant and O3-sensitive clones. The clonal differences in the level of CO2 × O3 interaction suggest a relationship between photosynthetic acclimation and background O3 concentration. 相似文献
28.
Advances in understanding ozone impact on forest trees: Messages from novel phytotron and free-air fumigation studies 总被引:1,自引:0,他引:1
R. Matyssek D.F. Karnosky G. Wieser E. Oksanen M. Kubiske H. Pretzsch 《Environmental pollution (Barking, Essex : 1987)》2010,158(6):1990-2006
Recent evidence from novel phytotron and free-air ozone (O3) fumigation experiments in Europe and America on forest tree species is highlighted in relation to previous chamber studies. Differences in O3 sensitivity between pioneer and climax species are examined and viewed for trees growing at the harsh alpine timberline ecotone. As O3 apparently counteracts positive effects of elevated CO2 and mitigates productivity increases, response is governed by genotype, competitors, and ontogeny rather than species per se. Complexity in O3 responsiveness increased under the influence of pathogens and herbivores. The new evidence does not conflict in principle with previous findings that, however, pointed to a low ecological significance. This new knowledge on trees' O3 responsiveness beyond the juvenile stage in plantations and forests nevertheless implies limited predictability due to complexity in biotic and abiotic interactions. Unravelling underlying mechanisms is mandatory for assessing O3 risks as an important component of climate change scenarios. 相似文献
29.
Johanna Riikonen Kevin E. Percy Mark E. Kubiske Elina Vapaavuori 《Environmental pollution (Barking, Essex : 1987)》2010,158(4):1029-1035
Betula papyrifera trees were exposed to elevated concentrations of CO2 (1.4 × ambient), O3 (1.2 × ambient) or CO2 + O3 at the Aspen Free-air CO2 Enrichment Experiment. The treatment effects on leaf surface characteristics were studied after nine years of tree exposure. CO2 and O3 increased epidermal cell size and reduced epidermal cell density but leaf size was not altered. Stomatal density remained unaffected, but stomatal index increased under elevated CO2. Cuticular ridges and epicuticular wax crystallites were less evident under CO2 and CO2 + O3. The increase in amorphous deposits, particularly under CO2 + O3, was associated with the appearance of elongated plate crystallites in stomatal chambers. Increased proportions of alkyl esters resulted from increased esterification of fatty acids and alcohols under elevated CO2 + O3. The combination of elevated CO2 and O3 resulted in different responses than expected under exposure to CO2 or O3 alone. 相似文献
30.
C. Calfapietra B. Gielen R. Ceulemans 《Environmental pollution (Barking, Essex : 1987)》2010,158(4):1095-1104
The use of agroforestry crops is a promising tool for reducing atmospheric carbon dioxide concentration through fossil fuel substitution. In particular, plantations characterised by high yields such as short rotation forestry (SRF) are becoming popular worldwide for biomass production and their role acknowledged in the Kyoto Protocol. While their contribution to climate change mitigation is being investigated, the impact of climate change itself on growth and productivity of these plantations needs particular attention, since their management might need to be modified accordingly. Besides the benefits deriving from the establishment of millions of hectares of these plantations, there is a risk of increased release into the atmosphere of volatile organic compounds (VOC) emitted in large amounts by most of the species commonly used. These hydrocarbons are known to play a crucial role in tropospheric ozone formation. This might represent a negative feedback, especially in regions already characterized by elevated ozone level. 相似文献